(i) Field of the Invention
The present invention relates to a barycentric position measuring apparatus which measures the barycentric position of a load when the load is applied to a load receiving board.
(ii) Description of the Related Art
A conventional barycentric position measuring apparatus which measures the barycentric position of a load when the load is applied to a load receiving board, as shown in a plan view in FIG. 7(a) showing the external appearance of the apparatus and a front view in FIG. 7(b) showing the external appearance of the apparatus, has a plurality of sensors 101, 102, 103 and 104 disposed at (x1, y1), (x2, y2), (x3, y3) and (x4, y4) so that a load is passed from a load receiving board 100, amplifies outputs w1, w2, w3 and w4 from the sensors 101, 102, 103 and 104 in turn, and calculates the barycentric position (Gx, Gy) of a load when the load is applied to the load receiving board 100 by use of the following expressions 3 and 4.Gx=(w1×x1+w2×x2+w3×x3+w4×x4)/(w1+w2+w3+w4)  (3)Gy=(w1×y1+w2×y2+w3×y3+w4×y4)/(w1+w2+w3+w4)  (4)
For example, a barycenter fluctuation meter as described in Patent Publication 1 and Patent Publication 2 as a kind of barycentric position measuring apparatus generally calculates a barycentric position in the manner as described above. Patent Publication 1
Japanese Patent Application Laid-Open No. 250822/1995 Patent Publication 2
Japanese Patent Application Laid-Open No. 250823/1995
However, the above barycentric position measuring apparatus has a problem that if the barycentric position of a load applied to the load receiving board 100 is displaced when the outputs w1, w2, w3 and w4 from the sensors 101, 102, 103 and 104 are amplified in turn, all changes in the outputs from the sensors which are caused by the displacement affect both the barycentric position Gx with respect to the x coordinate axis and the barycentric position Gy with respect to the y coordinate axis, thereby making calculation of an accurate barycentric position impossible.
Further, to obtain a high resolution for improvement of accuracy, the apparatus requires use of high-output sensors or amplifiers which greatly amplify outputs from sensors. Such sensors and amplifiers have a problem of being expensive due to their high performance.
Thus, an object of the present invention is to solve the above problems of the prior art and provide an inexpensive barycentric position measuring apparatus which measures a barycentric position accurately.